


Chaldea Nights

by No_Talker



Category: Fate/Grand Order
Genre: Anal Fingering, Anal Sex, Brother/Sister Incest, Doggy Style, F/M, Facials, Missionary Position, Public Masturbation, Sibling Incest, Vaginal Sex, Voyeurism, blowjob
Language: English
Status: Completed
Published: 2020-04-30
Updated: 2020-04-30
Packaged: 2021-03-01 21:42:30
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,512
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23904055
Author URL: https://archiveofourown.org/users/No_Talker/pseuds/No_Talker
Summary: Mash sees just how close her Masters really are.
Relationships: Female Fujimaru Ritsuka/Male Fujimaru Ritsuka
Comments: 10
Kudos: 66





	Chaldea Nights

**Author's Note:**

> This is going to be so bad...

Late at night, the halls of Chaldea where mostly empty. The few staff members walking around were those who were assigned to monitor for any potential singularities that may show up to threaten humanity. Most of them were located in the command and control center. In the residential area things are mostly subdued. Here, staff members and servants alike sleep away the days activity in order to ready themselves for the next days challenges. 

It's in these halls where one particular demi-servant quietly walks the halls. Mash Kyrielight was very used to walking these halls at night. She had done so for years ever since she was born. During those times she would just mindlessly walk the halls. Taking in the silence and listening to the cold arctic winds outside as she walked. But not this night. Slowly but surely, Mash makes her way to the far end of the residential area that was reserved for Master candidates. Of the 50 rooms available for Masters only 2 of them were currently in use. 

Masters Gudao and Gudako were the last masters of humanity after a surprise attack had killed or incapacitated all other potential master candidates. Together the two fraternal twins had resolved every singularity that had appeared to threaten humanity with the help of the servants contracted with them through Chaldea. Mash finally made her way to the last two doors of the masters area. Here were the rooms of her senpais. The first room, Gudako's room was shut closed with no light shinning from under the door. The next room, Gudao's room, however had light shinning from it. It also had the sounds of muffled moans coming from it. As Mash carefully moved closer the sounds got louder and her breathing got heavier. Pressing herself against the door, Mash listened to the sounds on the other side of the door intently. Then she finally heard a husky feminine voice moan.

"Harder!!"

Mash immediately recognized Gudako's voice. Hearing this, her body begins to heat up. Forbidden thoughts and images played in her head as she pressed herself harder to the door. Having lived in Chaldea all her life, Mash was privy to some hidden knowledge about Chaldea. For example she knew that this particular door had a malfunction in it's design. She knew that if someone were to press against the door and lift up the door could be manually opened from the outside without triggering the hissing sound of the gears opening the door. With practiced ease, Mash carefully lifted the door as she pressed herself against it. Slowly she moved the door to the side, affording her a small crack into the room inside.

Peeking inside she can see both Gudao and Gudako naked in the bed with each other. Gudao pushing himself in and out of his sister while Gudako laid on her back with her legs spread, giving her brother full access to her womanhood. With the door open the sounds of their love making was much clearer to hear. The sounds of sheets moving under bodies, the wet sound of sweaty bodies rubbing against each other and the hot breaths of the participants as they took pleasure from each others body. There was also the smell that emitted from the room as well. The raw smell of sex filled Mash's nostrils and made the tingling sensation between her legs stronger. 

For a while, all Mash did was simply stand there pressed against the door and watch them both through the crack. She took in the sight of their bodies as they made love to each other. She looked over Gudao's body. He was taller than both her and Gudako with broad shoulders and an athletic build. Not overly muscular but undeniably in shape. His face perfectly framed by his intense blue eyes and short dark hair. His muscles glistened with sweat as he pushed himself in and out of his twin sister at a steady pace, grunting in pleasure. His cock seemed to push impossibly deep into Gudaok's neatly trimmed womanhood has he took her over and over again at a steady pace. Gudako herself was, in Mash's opinion, a goddess reborn. Every inch of her body was a work of art. From her perfectly manicured toes, amazing legs, slim waist, flat stomach and full chest; everything about her was perfect. Her face was was a gorgeous visage with kissable lips, a button nose and noticeable eyelashes. Her beautiful golden eyes accentuate her shoulder length orange hair. Gudako had her hands balled into the sheets on either side of her as she enjoyed the feeling of her brothers considerable cock pushing into her depths. Moaning her every time he reached her deepest parts.

Mash watched the two of them pleasure each other until the tingling sensation between her legs became a burning need for release. With her breast pressed against the door Mash uses her left hand to slowly pull up her skirt. She then brought her right hand over her stomach and slowly reached down to her crotch till her fingers made contact. Her stockings were soaked with her arousal from just watching the obsene act in front of her. Mash was not wearing any panties under leggings so when she pushed a finger into herself it sank easily into her pussy without much resistance. Slowly, she started to rub herself through her stockings. Mash started off slow but quickly picked up speed the longer she watched, almost matching Gudao's speed as her keep ramming his cock into his sister. Mash toke note on how Gudao would move and reposition Gudako's hips so that his cock could move into her at different angles. This caused Gudako to all but scream her pleasure in approval. 

This was not the first time Mash had seen them like this. As far as Mash could tell they'd been doing this every night for quite a while. Probably before they both came to Chaldea. It made her wonder how long the two of them had been like this. Who was the one that first had such thoughts about each other? How did they confess their feelings toward the other? Did they always have such forbidden feelings for each other? What was their first time like with each other? How did they hide it from their family? Did any of their friends know about them? All these question seem to fill her mind at once as she watched the twins make love to each other. Mash had lived her entire life in Chaldea and was not experienced with sex outside of what she had read in various textbooks and novels. Nor did she have any siblings of her own so she had no point of reference to view their relationship with. However, she did know that incest was a morally taboo practice in modern society that was shunned throughout the world.

Incest

Upon thinking of the word Mash unknowingly slipped another finger into herself, speeding up her caresses while curling her fingers along her slit. It was such a forbidden word. A naughty word, Mash thought. Something you never talk about in proper company, let along indulge in. But right before her were the last two masters of humanity participating in it with reckless abandonment. Mash started to imagine herself in their position as she pleasured herslef. She imagined laying on her back as Gudao pushed his massive cock in and out of her needy pussy. Wracking her body with orgasm after orgasm like he was giving Gudako. She then imagined what it would feel like to have a cock and plunge it into Gudako's tight pussy. How warm and wet she would feel around her cock. This thought caused Mash to add a third finger to her slit and start rubbing herself even more intensely. She watched as Gudao bent down to Gudako and the two of them shared a passionate kiss while he still kept pumping in and out of her.

"This is wrong..." Mash whispered silently to the twins and herself, "Brothers and sisters shouldn't be doing such a thing...". She could feel the moisture from between her legs dripping down her soaked hand. Mash was certain that if anyone were to see her now it would look as if she had pissed herself if the feeling of how wet her stocking were was to go by. Gudao finally broke their kiss so that he could speak. 

"Gudako...sis...I'm about to cum!!" he said in between grunts. 

Gudako gasped back at him in response."Inside!! Cum inside me!! Cum inside your little sister, big brother!!" was all that she could manage before she arched her back from off the bed in orgasm. 

Hearing Gudako's exclamation and watching her body go rigid in orgasmic pleasure caused Mash's own orgasm to finally boil over. 

"Senpai, I'm also about too..." Mash whispered to herself as she finally thrust her fingers deep inside of her pussy. Closing her mouth as tightly as she could to avoid making any sounds, Mash came along with Gudako. She could feel on the front of her stocking a fresh source of wetness as she squirted into her stockings. Gudao grunted once and slammed his hips into Gudako and stayed locked there with his cock reaching as deeply as it could inside of her. Spurt after spurt of his hot cum flooded his twin sisters insides, causing her to have another orgasm. They stayed like that for a few seconds until Gudako's insides were completely flooded with her brother's cum. Gudao raised up to his knees and removed his still spasming cock from his sister's warm embrace. Taking hold of his cock he stroked himself quickly as several more ropes of cum erupted from his cock and he began to coat Gudako's pussy, stomach and chest with his seemingly endless supply of cum. The final shot of cum making it all the way to her face and landing directly on her perfect lips. Gudako finally settled back down onto the bed and started breathing heavily as she came back down from her high. She looked down at her cum covered body and smiled at the sight of her brother marking her in his passion. Using her right hand, she slowly follows the trail of cum from her stomach, over her breast and to her lips. She gathered all the cum on her face and pushed it into her mouth, sucking her fingers greedily like she was having a rare treat. All the while giving Gudao a look of lust and wanting.

Gudao knelt there and basked in the sight before him. His sister, laid out before him, pussy dripping with his cum, her body covered in his cum and her sensually sucking his cum from her fingers while staring at him with eyes that screamed sexual desire. Everything he saw before him was utterly arousing and he was not surprised to see that his erection had not yet gone down and was still ready to go for more. Cumming once was never enough for him even when he was younger. Gudako had also noticed her brother's still throbbing erection and smirked at him before raising up on her hands and knees so that her face was now level with his cock. Reaching her cum covered hand up she grabbed hold of his cock and started to stroke it. Enjoying the feeling of his penis in her hand for a while before leaning forward and taking his cock into her mouth. Moaning as she tasted both their combined arousal mixed in with each other. Gudao leaned his head back and enjoyed the sensation of Gudako's mouth on his cock, putting his right hand on the back of her head so he could feel her bobbing up and down his pole.

Mash, having finally recovered from her own orgasm, went about quietly pushing the door back into place. Now that they were taking a short break she didn't want to take the risk that one of them would notice the open door. After making sure that the door was back in it's proper place Mash took out a hand cloth and quickly wiped up the wet spot in front of the door and started to make her way back down the hall to her own room as quietly as she could. Her entire trip spent replaying what she had just witnessed over and over again in her head. This of course only made her want to please herself more and looking forward to spying on them some more.

***

Gudao looked over at the door and saw that the crack was no longer there, meaning that Mash had most likely left. He looked down at his beautiful sister lovingly sucking his cock and smiled at her.

"Cum inside your little sister, big brother", he quoted her with an amused look on his face. "Aren't you the one who keeps reminding me that you were born first?". Gudako released her brother's cock from her mouth with a wet pop. She rubbed it against her cheek as she looked up to him.

"Had to put on a show for our cute little Mash to enjoy. Don't you agree?" Gudako smiled. 

Ever since they were younger the twins had become adept at hiding their secret relationship from others who wouldn't understand. So when Mash started spying on them they immediately noticed. At first, they were worried about what they should do about being discovered. But when they realized that she was into it they decided to keep going like they hadn't noticed. The knowledge of being watched had made the sex that night mind blowing. So ever since that day they have continued as if nothing had happened. During the day Gudako and Gudao would pretend that nothing had ever changed. At night they continued to enjoy each others bodies while under the lustful gaze of their cute little Mash.

"But enough about her for now." Gudako returned to servicing her brother's cock once more. Gudao moaned in pleasure as he felt his sisters hot and wet mouth get back to work on his cock. Making sure to lather plenty of saliva on it as she could before taking it out of her mouth and turning around. Now her perfect ass was in full view for her brother to see. With moist fingers, Gudako reaches back to her ass and starts to tease her anus open with slow and methodical thrust in and out of it. Once her ass was sufficiently loosened she reached back with both her hands and spread her ass cheeks. "Now I want to feel my Big Brother's cock in my tight little ass." Gudako said looking back at her brother with a coy grin.

Gudao smiled. Positioning his cock to his sister's rosebud he was met with no resistance as he slow slide his cock into his sister's tight ass. The twins both let out a moan before the sounds of sex filled the room once again.

**Author's Note:**

> If you see any grammatical mistakes please point them out to me. I will smash my head into the wall then correct them. Thanks for reading my nonsense.


End file.
